9h6e

Complex of Histidine-containing phosphotransfer 1 (AHP1) and Response regulator 1 (ARR1) from A. thaliana

spinqualitylabelsall models 9h6e, resolution 2.87Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9h6e is a 4 chain structure with sequence from Arabidopsis thaliana. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.87Å Ligands: EDO, GOL, OXM Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function AHP1_ARATH Functions as two-component phosphorelay mediators between cytokinin sensor histidine kinases and response regulators (B-type ARRs). Plays an important role in propagating cytokinin signal transduction through the multistep His-to-Asp phosphorelay. Publication Abstract from PubMed Plants use multi-step phosphorelay (MSP) systems in response to exogenous and endogenous stimuli. Cytokinin and ethylene are among the factors that engage MSP signaling cascades but examples independent of phytohormones also exist. The MSP signaling involves four consecutive phosphorylation events at: (i) the kinase domain of the sensory histidine kinase, (ii) the receiver domain of the latter protein, (iii) the histidine-containing phosphotransfer protein, and (iv) the response regulator. In Arabidopsis thaliana, there are eight canonical histidine kinases, five histidine-containing phosphotransfer proteins (AHPs), one pseudo AHP, and 23 response regulators (ARRs). This redundancy suggests complex interactions between signaling pathways, including those involved in phytohormone cross-talk. To bring new insights at the molecular level, we investigated the structural and biophysical characteristics of the AHP1/ARR1 complex. ARR1, a type-B ARR, contains the GARP domain for DNA binding, in addition to the canonical receiver domain that mediates AHP1 interaction. We compared the ARR1 affinities across all five active AHPs and found a modest, two-fold higher affinity for AHP1. This result suggests that while ARR1 shows a slight preference for AHP1, it can also interact with AHP2-5, which potentially makes ARR1 a central node in signaling and a cross-talk modulator. In addition, we discuss the oligomerization state of AHP and related proteins utilizing all available experimental data to conclude that free AHPs are most likely monomeric. ARR1 and AHP interactions in the multi-step phosphorelay system.,Tran LH, Ruszkowski M Front Plant Sci. 2025 Feb 27;16:1537021. doi: 10.3389/fpls.2025.1537021. , eCollection 2025. PMID:40084109 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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